Move / Scale

Subtitles synchronization - remarks

Synchronization is probably the most often used function, there are various versions of the same movie in the Internet and also various versions of subtitles. However often the only available subtitles are for a different version of movie. In most cases these simple functions will be enough.

When I download subtitles and they do not fit with the movie, I do the following steps and in most cases the subtitles are synchronized in no-time.

1. Play the movie and find the place where the characters speak their first lines from the first subtitle, use precision seeking and bookmark to remember the value.
2. Use the Offset auto-value and Move the subtitles.
3. Play the movie and seek through it to see if the subtitles at the end are synchronized. If they are not, proceed to step 4
4. Reload the subtitles to discard previous changes. In most cases the subtitles are for a different framerate (see the framerate remarks lower). If the FPS of the movie is 23.976 (NTSC), try a conversion from 25.0 to 23.976 and if the movie FPS is 25.0, try the other conversion. 
5. Seek through the movie to see if the subtitles are synchronous. If they aren't, select the first subtitle and use the bookmarked value from step 1. Use Offset auto-value and Move the subtitles. 
6. If they are not synchronous yet, either search for another subtitles or use the Resynchronization function. There may be different reasons for this problem, the most probable is that the subtitles are for a theatrical version of the movie and you have either DC or Unrated version.

1 Move subtitles

Move the subtitles in time. Use this if the subtitles have a constant time offset - they are showing too early or too late. The controls are:

• Edit box - enter the time offset you want to add to the subtitles. Enter negative value if the subtitles start too late, positive if they start too early. The button offers 3 automated values:
• Offset (current position - selected subtitle's start) - For example the movie position is 123th frame and the selected subtitle starts at 130th frame, the value will be 123-130=-7
• Subtitle start and Subtitle end - the values of selected subtitle's timestamps
• Only selected - move only subtitles marked in the main list
• Move - do the move operation

2 Change speed

Change the speed of subtitles. Use this if the subtitles are appearing more lately or early as the movie progress (they are running slower or faster). The controls are:

• Edit box - enter the desired speed in %. Experiment with the value, try the subtitles in player and if the speed change is not precise, reload the subtitles and modify this value a little
• Only selected - move only subtitles marked in the main list
• Change - change the speed by the value entered in the edit box

3 Change length

Change speed using ratio between Old and New length. The settings are:

• New length - New length of the movie
• Old length - Old length of the movie (automatically filled when movie is loaded)

By clicking the Change button, new speed is calculated and set to Speed change box. the Move by box is cleared and then a general Adjust is performed.

4 Recalculate FPS

Change speed using Old and New FPS ratio (to adjust subtitles for a movie with different frame rate). The settings are:

• New FPS - New frame rate - the frame rate of the new movie
• Old FPS - Old frame rate - the framerate of the subtitles

By clicking the Change button, new speed is calculated and set to Speed change box. the Move by box is cleared and then a general Adjust is performed.

Remarks about frame rate:

Most movies have a FPS of 25.0 (PAL), 23.976 (NTSC) far less movies have also 29.97 (NTSC). Frame-based subtitles will fit with BOTH PAL (25.) and NTSC (23.976) movies WITHOUT any change. This is because the theatrical movie (with FPS of 24.0) is either sped-up a little (for PAL 25.0) or slowed down (for NTSC 23.976; the NTSC conversion is more complex, search the Internet for more information). The sound is ALSO sped-up or slowed down so the subtitles will fit to both movies.

Time-based subtitles however need to be converted between PAL and NTSC. When using time based subtitles (e.g. SRT), the 29.97 and 23.976 FPS are EQUAL and you must ALWAYS use 23.976 when converting from 25.0. (this is because of the way the theatrical movies are converted to NTSC standard; search the Internet for IVTC for more details).